481 lines
20 KiB
C++
481 lines
20 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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* interface that provides scroll APIs implemented by scrollable frames
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*/
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#ifndef nsIScrollFrame_h___
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#define nsIScrollFrame_h___
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#include "nsCoord.h"
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#include "DisplayItemClip.h"
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#include "ScrollStyles.h"
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#include "mozilla/Maybe.h"
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#include "mozilla/gfx/Point.h"
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#include "nsIScrollbarMediator.h"
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#include "Units.h"
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#include "FrameMetrics.h"
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#define NS_DEFAULT_VERTICAL_SCROLL_DISTANCE 3
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#define NS_DEFAULT_HORIZONTAL_SCROLL_DISTANCE 5
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class nsBoxLayoutState;
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class nsIScrollPositionListener;
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class nsIFrame;
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class nsPresContext;
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class nsIContent;
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class nsRenderingContext;
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class nsIAtom;
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class nsDisplayListBuilder;
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namespace mozilla {
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struct ContainerLayerParameters;
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namespace layers {
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class Layer;
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} // namespace layers
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} // namespace mozilla
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/**
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* Interface for frames that are scrollable. This interface exposes
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* APIs for examining scroll state, observing changes to scroll state,
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* and triggering scrolling.
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*/
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class nsIScrollableFrame : public nsIScrollbarMediator {
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public:
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typedef mozilla::CSSIntPoint CSSIntPoint;
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typedef mozilla::ContainerLayerParameters ContainerLayerParameters;
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typedef mozilla::layers::FrameMetrics FrameMetrics;
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typedef mozilla::layers::ScrollSnapInfo ScrollSnapInfo;
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NS_DECL_QUERYFRAME_TARGET(nsIScrollableFrame)
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/**
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* Get the frame for the content that we are scrolling within
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* this scrollable frame.
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*/
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virtual nsIFrame* GetScrolledFrame() const = 0;
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/**
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* Get the styles (NS_STYLE_OVERFLOW_SCROLL, NS_STYLE_OVERFLOW_HIDDEN,
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* or NS_STYLE_OVERFLOW_AUTO) governing the horizontal and vertical
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* scrollbars for this frame.
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*/
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virtual mozilla::ScrollStyles GetScrollStyles() const = 0;
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enum { HORIZONTAL = 0x01, VERTICAL = 0x02 };
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/**
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* Return the scrollbars which are visible. It's OK to call this during reflow
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* of the scrolled contents, in which case it will reflect the current
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* assumptions about scrollbar visibility.
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*/
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virtual uint32_t GetScrollbarVisibility() const = 0;
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/**
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* Returns the directions in which scrolling is perceived to be allowed.
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* A direction is perceived to be allowed if there is a visible scrollbar
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* for that direction or if the scroll range is at least one device pixel.
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*/
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uint32_t GetPerceivedScrollingDirections() const;
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/**
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* Return the actual sizes of all possible scrollbars. Returns 0 for scrollbar
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* positions that don't have a scrollbar or where the scrollbar is not visible.
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* Do not call this while this frame's descendants are being reflowed, it won't be
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* accurate.
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*/
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virtual nsMargin GetActualScrollbarSizes() const = 0;
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/**
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* Return the sizes of all scrollbars assuming that any scrollbars that could
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* be visible due to overflowing content, are. This can be called during reflow
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* of the scrolled contents.
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*/
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virtual nsMargin GetDesiredScrollbarSizes(nsBoxLayoutState* aState) = 0;
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/**
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* Return the sizes of all scrollbars assuming that any scrollbars that could
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* be visible due to overflowing content, are. This can be called during reflow
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* of the scrolled contents.
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*/
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virtual nsMargin GetDesiredScrollbarSizes(nsPresContext* aPresContext,
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nsRenderingContext* aRC) = 0;
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/**
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* Return the width for non-disappearing scrollbars.
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*/
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virtual nscoord
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GetNondisappearingScrollbarWidth(nsPresContext* aPresContext,
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nsRenderingContext* aRC,
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mozilla::WritingMode aWM) = 0;
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/**
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* GetScrolledRect is designed to encapsulate deciding which
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* directions of overflow should be reachable by scrolling and which
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* should not. Callers should NOT depend on it having any particular
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* behavior (although nsXULScrollFrame currently does).
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*
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* This should only be called when the scrolled frame has been
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* reflowed with the scroll port size given in mScrollPort.
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*
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* Currently it allows scrolling down and to the right for
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* nsHTMLScrollFrames with LTR directionality and for all
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* nsXULScrollFrames, and allows scrolling down and to the left for
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* nsHTMLScrollFrames with RTL directionality.
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*/
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virtual nsRect GetScrolledRect() const = 0;
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/**
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* Get the area of the scrollport relative to the origin of this frame's
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* border-box.
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* This is the area of this frame minus border and scrollbars.
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*/
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virtual nsRect GetScrollPortRect() const = 0;
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/**
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* Get the offset of the scrollport origin relative to the scrolled
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* frame origin. Typically the position will be non-negative.
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* This will always be a multiple of device pixels.
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*/
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virtual nsPoint GetScrollPosition() const = 0;
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/**
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* As GetScrollPosition(), but uses the top-right as origin for RTL frames.
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*/
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virtual nsPoint GetLogicalScrollPosition() const = 0;
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/**
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* Get the area that must contain the scroll position. Typically
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* (but not always, e.g. for RTL content) x and y will be 0, and
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* width or height will be nonzero if the content can be scrolled in
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* that direction. Since scroll positions must be a multiple of
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* device pixels, the range extrema will also be a multiple of
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* device pixels.
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*/
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virtual nsRect GetScrollRange() const = 0;
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/**
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* Get the size of the scroll port to use when clamping the scroll
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* position.
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*/
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virtual nsSize GetScrollPositionClampingScrollPortSize() const = 0;
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/**
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* Return how much we would try to scroll by in each direction if
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* asked to scroll by one "line" vertically and horizontally.
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*/
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virtual nsSize GetLineScrollAmount() const = 0;
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/**
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* Return how much we would try to scroll by in each direction if
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* asked to scroll by one "page" vertically and horizontally.
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*/
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virtual nsSize GetPageScrollAmount() const = 0;
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/**
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* When a scroll operation is requested, we ask for instant, smooth,
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* smooth msd, or normal scrolling.
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*
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* SMOOTH scrolls have a symmetrical acceleration and deceleration curve
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* modeled with a set of splines that guarantee that the destination will be
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* reached over a fixed time interval. SMOOTH will only be smooth if smooth
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* scrolling is actually enabled. This behavior is utilized by keyboard and
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* mouse wheel scrolling events.
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*
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* SMOOTH_MSD implements a physically based model that approximates the
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* behavior of a mass-spring-damper system. SMOOTH_MSD scrolls have a
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* non-symmetrical acceleration and deceleration curve, can potentially
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* overshoot the destination on intermediate frames, and complete over a
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* variable time interval. SMOOTH_MSD will only be smooth if cssom-view
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* smooth-scrolling is enabled.
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*
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* INSTANT is always synchronous, NORMAL can be asynchronous.
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*
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* If an INSTANT scroll request happens while a SMOOTH or async scroll is
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* already in progress, the async scroll is interrupted and we instantly
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* scroll to the destination.
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*
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* If an INSTANT or SMOOTH scroll request happens while a SMOOTH_MSD scroll
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* is already in progress, the SMOOTH_MSD scroll is interrupted without
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* first scrolling to the destination.
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*/
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enum ScrollMode { INSTANT, SMOOTH, SMOOTH_MSD, NORMAL };
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/**
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* Some platforms (OSX) may generate additional scrolling events even
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* after the user has stopped scrolling, simulating a momentum scrolling
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* effect resulting from fling gestures.
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* SYNTHESIZED_MOMENTUM_EVENT indicates that the scrolling is being requested
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* by such a synthesized event and may be ignored if another scroll has
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* been started since the last actual user input.
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*/
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enum ScrollMomentum { NOT_MOMENTUM, SYNTHESIZED_MOMENTUM_EVENT };
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/**
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* @note This method might destroy the frame, pres shell and other objects.
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* Clamps aScrollPosition to GetScrollRange and sets the scroll position
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* to that value.
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* @param aRange If non-null, specifies area which contains aScrollPosition
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* and can be used for choosing a performance-optimized scroll position.
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* Any point within this area can be chosen.
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* The choosen point will be as close as possible to aScrollPosition.
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*/
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virtual void ScrollTo(nsPoint aScrollPosition, ScrollMode aMode,
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const nsRect* aRange = nullptr,
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nsIScrollbarMediator::ScrollSnapMode aSnap
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= nsIScrollbarMediator::DISABLE_SNAP) = 0;
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/**
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* @note This method might destroy the frame, pres shell and other objects.
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* Scrolls to a particular position in integer CSS pixels.
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* Keeps the exact current horizontal or vertical position if the current
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* position, rounded to CSS pixels, matches aScrollPosition. If
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* aScrollPosition.x/y is different from the current CSS pixel position,
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* makes sure we only move in the direction given by the difference.
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*
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* When aMode is SMOOTH, INSTANT, or NORMAL, GetScrollPositionCSSPixels (the
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* scroll position after rounding to CSS pixels) will be exactly
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* aScrollPosition at the end of the scroll animation.
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*
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* When aMode is SMOOTH_MSD, intermediate animation frames may be outside the
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* range and / or moving in any direction; GetScrollPositionCSSPixels will be
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* exactly aScrollPosition at the end of the scroll animation unless the
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* SMOOTH_MSD animation is interrupted.
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*/
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virtual void ScrollToCSSPixels(const CSSIntPoint& aScrollPosition,
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nsIScrollableFrame::ScrollMode aMode
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= nsIScrollableFrame::INSTANT) = 0;
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/**
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* @note This method might destroy the frame, pres shell and other objects.
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* Scrolls to a particular position in float CSS pixels.
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* This does not guarantee that GetScrollPositionCSSPixels equals
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* aScrollPosition afterward. It tries to scroll as close to
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* aScrollPosition as possible while scrolling by an integer
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* number of layer pixels (so the operation is fast and looks clean).
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*/
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virtual void ScrollToCSSPixelsApproximate(const mozilla::CSSPoint& aScrollPosition,
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nsIAtom *aOrigin = nullptr) = 0;
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/**
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* Returns the scroll position in integer CSS pixels, rounded to the nearest
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* pixel.
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*/
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virtual CSSIntPoint GetScrollPositionCSSPixels() = 0;
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/**
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* When scrolling by a relative amount, we can choose various units.
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*/
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enum ScrollUnit { DEVICE_PIXELS, LINES, PAGES, WHOLE };
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/**
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* @note This method might destroy the frame, pres shell and other objects.
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* Modifies the current scroll position by aDelta units given by aUnit,
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* clamping it to GetScrollRange. If WHOLE is specified as the unit,
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* content is scrolled all the way in the direction(s) given by aDelta.
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* @param aOverflow if non-null, returns the amount that scrolling
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* was clamped by in each direction (how far we moved the scroll position
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* to bring it back into the legal range). This is never negative. The
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* values are in device pixels.
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*/
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virtual void ScrollBy(nsIntPoint aDelta, ScrollUnit aUnit, ScrollMode aMode,
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nsIntPoint* aOverflow = nullptr,
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nsIAtom* aOrigin = nullptr,
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ScrollMomentum aMomentum = NOT_MOMENTUM,
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nsIScrollbarMediator::ScrollSnapMode aSnap
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= nsIScrollbarMediator::DISABLE_SNAP) = 0;
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/**
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* Perform scroll snapping, possibly resulting in a smooth scroll to
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* maintain the scroll snap position constraints. Velocity sampled from
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* main thread scrolling is used to determine best matching snap point
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* when called after a fling gesture on a trackpad or mouse wheel.
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*/
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virtual void ScrollSnap() = 0;
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/**
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* @note This method might destroy the frame, pres shell and other objects.
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* This tells the scroll frame to try scrolling to the scroll
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* position that was restored from the history. This must be called
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* at least once after state has been restored. It is called by the
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* scrolled frame itself during reflow, but sometimes state can be
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* restored after reflows are done...
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* XXX should we take an aMode parameter here? Currently it's instant.
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*/
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virtual void ScrollToRestoredPosition() = 0;
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/**
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* Add a scroll position listener. This listener must be removed
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* before it is destroyed.
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*/
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virtual void AddScrollPositionListener(nsIScrollPositionListener* aListener) = 0;
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/**
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* Remove a scroll position listener.
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*/
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virtual void RemoveScrollPositionListener(nsIScrollPositionListener* aListener) = 0;
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/**
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* Internal method used by scrollbars to notify their scrolling
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* container of changes.
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*/
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virtual void CurPosAttributeChanged(nsIContent* aChild) = 0;
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/**
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* Allows the docshell to request that the scroll frame post an event
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* after being restored from history.
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*/
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NS_IMETHOD PostScrolledAreaEventForCurrentArea() = 0;
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/**
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* Returns true if this scrollframe is being "actively scrolled".
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* This basically means that we should allocate resources in the
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* expectation that scrolling is going to happen.
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*/
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virtual bool IsScrollingActive(nsDisplayListBuilder* aBuilder) = 0;
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/**
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* Returns true if the scrollframe is currently processing an async
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* or smooth scroll.
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*/
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virtual bool IsProcessingAsyncScroll() = 0;
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/**
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* Call this when the layer(s) induced by active scrolling are being
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* completely redrawn.
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*/
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virtual void ResetScrollPositionForLayerPixelAlignment() = 0;
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/**
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* Was the current presentation state for this frame restored from history?
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*/
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virtual bool DidHistoryRestore() const = 0;
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/**
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* Clear the flag so that DidHistoryRestore() returns false until the next
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* RestoreState call.
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* @see nsIStatefulFrame::RestoreState
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*/
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virtual void ClearDidHistoryRestore() = 0;
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/**
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* Determine if the passed in rect is nearly visible according to the frame
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* visibility heuristics for how close it is to the visible scrollport.
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*/
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virtual bool IsRectNearlyVisible(const nsRect& aRect) = 0;
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/**
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* Expand the given rect taking into account which directions we can scroll
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* and how far we want to expand for frame visibility purposes.
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*/
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virtual nsRect ExpandRectToNearlyVisible(const nsRect& aRect) const = 0;
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/**
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* Returns the origin that triggered the last instant scroll. Will equal
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* nsGkAtoms::apz when the compositor's replica frame metrics includes the
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* latest instant scroll.
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*/
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virtual nsIAtom* LastScrollOrigin() = 0;
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/**
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* Sets a flag on the scrollframe that indicates the current scroll origin
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* has been sent over in a layers transaction, and subsequent changes to
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* the scroll position by "weaker" origins are permitted to overwrite the
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* the scroll origin. Scroll origins that nsLayoutUtils::CanScrollOriginClobberApz
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* returns false for are considered "weaker" than scroll origins for which
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* that function returns true.
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*/
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virtual void AllowScrollOriginDowngrade() = 0;
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/**
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* Returns the origin that triggered the last smooth scroll.
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* Will equal nsGkAtoms::apz when the compositor's replica frame
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* metrics includes the latest smooth scroll. The compositor will always
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* perform an instant scroll prior to instantiating any smooth scrolls
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* if LastScrollOrigin and LastSmoothScrollOrigin indicate that
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* an instant scroll and a smooth scroll have occurred since the last
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* replication of the frame metrics.
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*
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* This is set to nullptr to when the compositor thread acknowledges that
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* the smooth scroll has been started. If the smooth scroll has been stomped
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* by an instant scroll before the smooth scroll could be started by the
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* compositor, this is set to nullptr to clear the smooth scroll.
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*/
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virtual nsIAtom* LastSmoothScrollOrigin() = 0;
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/**
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* Returns the current generation counter for the scroll. This counter
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* increments every time the scroll position is set.
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*/
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virtual uint32_t CurrentScrollGeneration() = 0;
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/**
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* LastScrollDestination returns the destination of the most recently
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* requested smooth scroll animation.
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*/
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virtual nsPoint LastScrollDestination() = 0;
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/**
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* Clears the "origin of last scroll" property stored in this frame, if
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* the generation counter passed in matches the current scroll generation
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* counter.
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*/
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virtual void ResetScrollInfoIfGeneration(uint32_t aGeneration) = 0;
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/**
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* Determine whether it is desirable to be able to asynchronously scroll this
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* scroll frame.
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*/
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virtual bool WantAsyncScroll() const = 0;
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/**
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* aLayer's animated geometry root is this frame. If there needs to be a
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* ScrollMetadata contributed by this frame, append it to aOutput.
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*/
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virtual mozilla::Maybe<mozilla::layers::ScrollMetadata> ComputeScrollMetadata(
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mozilla::layers::Layer* aLayer,
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nsIFrame* aContainerReferenceFrame,
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const ContainerLayerParameters& aParameters,
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const mozilla::DisplayItemClip* aClip) const = 0;
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/**
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* If this scroll frame is ignoring viewporting clipping
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*/
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virtual bool IsIgnoringViewportClipping() const = 0;
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/**
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* Mark the scrollbar frames for reflow.
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*/
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virtual void MarkScrollbarsDirtyForReflow() const = 0;
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virtual void SetTransformingByAPZ(bool aTransforming) = 0;
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virtual bool IsTransformingByAPZ() const = 0;
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/**
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* Notify this scroll frame that it can be scrolled by APZ. In particular,
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* this is called *after* the APZ code has created an APZC for this scroll
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* frame and verified that it is not a scrollinfo layer. Therefore, setting an
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* async transform on it is actually user visible.
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*/
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virtual void SetScrollableByAPZ(bool aScrollable) = 0;
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/**
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* Notify this scroll frame that it can be zoomed by APZ.
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*/
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virtual void SetZoomableByAPZ(bool aZoomable) = 0;
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/**
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* Whether or not this frame uses containerful scrolling.
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*/
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virtual bool UsesContainerScrolling() const = 0;
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/**
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* Determine if we should build a scrollable layer for this scroll frame and
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* return the result. It will also record this result on the scroll frame.
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* Pass the dirty rect in aDirtyRect. On return it will be set to the
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* displayport if there is one (ie the dirty rect that should be used).
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* This function may create a display port where one did not exist before if
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* aAllowCreateDisplayPort is true. It is only allowed to be false if there
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* has been a call with it set to true before on the same paint.
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*/
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virtual bool DecideScrollableLayer(nsDisplayListBuilder* aBuilder,
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nsRect* aDirtyRect,
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bool aAllowCreateDisplayPort) = 0;
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/**
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* Notification that this scroll frame is getting its frame visibility updated.
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*/
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virtual void NotifyApproximateFrameVisibilityUpdate() = 0;
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/**
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* Returns true if this scroll frame had a display port at the last frame
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* visibility update and fills in aDisplayPort with that displayport. Returns
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* false otherwise, and doesn't touch aDisplayPort.
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*/
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virtual bool GetDisplayPortAtLastApproximateFrameVisibilityUpdate(nsRect* aDisplayPort) = 0;
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/**
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* This is called when a descendant scrollframe's has its displayport expired.
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* This function will check to see if this scrollframe may safely expire its
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* own displayport and schedule a timer to do that if it is safe.
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*/
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virtual void TriggerDisplayPortExpiration() = 0;
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/**
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* Returns information required to determine where to snap to after a scroll.
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*/
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virtual ScrollSnapInfo GetScrollSnapInfo() const = 0;
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virtual void SetScrollsClipOnUnscrolledOutOfFlow() = 0;
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};
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#endif
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